This has been happening for a couple months on my Subaru, drives great no issues and done quite a bit of servicing recently on the fluids and filters, but when driving sometimes I put my foot down nothing happens and even if I put it down almost all the way, but then it suddenly takes off. What does this sound like? I always fill up with 98, everyday at high speeds so I don't think it would be something like a clogged injector. Maybe a fuel pump failing?